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Biomedical subjects

I Faé

Publications and source records attributed to I Faé.

At least 19 recordsLinked to original sources
PubMed2005

Impact of HLA class I high-resolution mismatches on chronic graft-versus-host disease and survival of patients given hematopoietic stem cell grafts from unrelated donors.

There is consensus that matching of unrelated donors (URD) and patients for HLA class II alleles improves the outcome of hematopoietic stem cell transplantation (HSCT). However, the significance of HLA class I allelic mismatches for transplant outcome is under discussion and reports on long-term effects like chronic graft-versus-host disease (GVHD) are rare. Thus, we investigated the association of human leukocyte antigen (HLA) class I allele mismatches and outcome in 144 patients given HSCT from URD who were matched for HLA-DRB1, DRB3/4/5, and DQB1 alleles. The risk of chronic GVHD was significantly increased in patients with class I mismatched donors, the mismatch either detected by low- or high-resolution typing. A single HLA class I allele mismatch significantly increased the risk of chronic GVHD in multivariate analysis. Overall survival was significantly reduced in patient/donor pairs with more than one-allele class I mismatch. Thus, selection of unrelated donors for transplantation should be based on high-resolution HLA class I typing.

Adolescent↗
PubMed2004

A novel HLA-DRB1*13 allele (DRB1*1357) identified by polymerase chain reaction with sequence-specific primers and direct sequencing.

We describe the identification of a new DRB1*13 allele, DRB1*1357*, found in two Austrian Caucasian individuals. The novel allele was initially suspected because analysis with sequence-specific primers resulted in an unusual pattern of amplification. Thereafter, exon 2 was further characterized by sequence-based typing. The nucleotide sequence of DRB1*1357 is identical to DRB1*1319 except for a single substitution in codon 47 (TAC to TTC) leading to a change from phenylalanine to tyrosine.

Alleles↗
PubMed2004

HLA-B*8102*, a new allele found in an external proficiency testing scheme.

A new human leukocyte allele HLA-B*8102 has been identified in a cell provided by the UCLA International Cell Exchange scheme. The nucleotide sequences of exons 2 and 3 of the new allele are identical with HLA-B*8101. Four nucleotide differences, however, are observed in exon 1, three of them representing non-synonymous base changes.

Amino Acid Sequence↗
PubMed2000

Serological and nucleotide sequence analysis of HLA-A*6812.

We describe a novel HLA-A allele, HLA-A*6812. HLA-typing of a patient was performed by serology and by DNA-based analyses. Cloning and sequencing of exons 2 and 3 revealed that the genotype consisted of a common HLA-A*0101 allele and the novel HLA-A*6812 allele. HLA*6812 is identical to HLA-A*68012 except for a single non-synonymous nucleotide substitution leading to an exchange of a threonine to an isoleucine residue at position 142 of the HLA-class I alpha chain. The allele was also found in the patient's mother. The novel HLA-A68 molecule is recognised by some but not all of our HLA-A28-specific sera. These results confirm that position 142 is important for the serological properties of the HLA-A molecule.

Alleles↗
PubMed1999

Characterization of a novel HLA-A*24 allele containing an HLA-A*03 sequence motif.

HLA-A*2418 is described for the first time. It segregates in a Mendelian fashion. Serological analyses indicate that the new allele encodes epitopes from both HLA-A9 and -A3 specificities. Results from nucleotide sequencing analyses of polymerase chain reaction (PCR) amplification products derived from genomic and cDNA are compatible with those findings.

Alleles↗
PubMed1997

MUC18/MCAM (CD146), an activation antigen of human T lymphocytes.

Extravasation and tissue infiltration of leukocytes and metastatic tumor cells require the regulated expression and function of adhesive and pro-proteolytic surface molecules. We demonstrate here that human T cells, upon activation, neo-express the melanoma metastasis-associated surface molecule MUC18/melanoma cell adhesion molecule (MCAM). Expression of MUC18/MCAM (CD146) on T cells could be identified with two mAbs (541-10B2 and 541-2E5) obtained after immunization with HUT102 T cells and found to react with activated T cells. The specificity of our mAbs for MUC18/MCAM (CD146) was revealed by 1) definition of the appropriate molecular mass of approximately 110 kDa unreduced and 120 kDa reduced, 2) reactivity of mAbs with MUC18/MCAM (CD146) cDNA-transfected mouse L cells, 3) conclusive crosswise immunoblotting experiments with MUC18/MCAM (CD146)-specific mAbs, and 4) N-terminal amino acid sequencing of precipitated protein. In vitro activation by PHA caused neo-expression of MUC18/MCAM (CD146) on peripheral blood T cells within 1 day of stimulation, reaching a maximum on day 3. In vivo expression of MUC18/MCAM (CD146) was confirmed on CD3+ T cells infiltrating delayed-type hypersensitivity lesions of the skin, on synovial fluid T cells of rheumatoid arthritis patients, and on distinct T leukemia cells. MUC18/MCAM (CD146) cell surface expression on activated T cells is mirrored by the presence of specific mRNA. Leukocytes of healthy donors do not show significant MUC18/MCAM (CD146) expression. The finding that MUC18/MCAM (CD146) is also expressed on activated T cells might suggest that this adhesion molecule is involved in the extravasation and/or homing of activated T cells.

Antibodies, Monoclonal↗
PubMed1996

A new polymorphism of arylsulfatase A within the coding region.

A 10-year-old boy with juvenile metachromatic leukodystrophy (MLD) presented with the 459 + 1G-->A arylsulfatase A (ASA) mutation on one allele. To detect his complete genotype, the other ASA allele was sequenced and a T-to-C transition at nucleotide 376 in exon 2 was identified. This missense mutation results in a substitution of leucine 76 by proline. Of 20 MLD unrelated controls, 18 carried the L/P76 mutation either in the homozygous (n = 6) or heterozygous (n = 12) state. The presence or absence of L/P76 did not influence leukocyte ASA activity or urinary sulfatide excretion. Apparently, the substitution of leucine 76 by proline is a common ASA polymorphism, neither being related to MLD nor creating ASA pseudodeficiency. However, because of its frequency and location, L/P76 may be of particular importance in genetic studies requiring the differentiation of the ASA alleles within a kindred. Further studies are directed to the as yet unresolved genotype of the index case with juvenile MLD.

Alleles↗
PubMed1996

Ligation based HLA-B*27 typing.

We have established a ligation based typing method to detect HLA-B*27 alleles at the DNA level. The method requires amplification of exon 2 of the HLA-B locus from genomic DNA by the polymerase catalyzed chain reaction (PCR) using group specific primers. An aliquot of the PCR amplification product, heat stable ligase and a pair of oligonucleotide probes, designed to hybridize adjacently to HLA-B*27 specific sequences of the amplified DNA are subsequently thermocycled. If the probes are perfectly complementary they become ligated otherwise they stay separated. The ligation of probes can be detected through their different labels by an enzyme linked immunosorbent assay (ELISA). Ligation based detection of beta-actin sequences which have been co-amplified serves as positive control for each PCR reaction. We observed complete concordance when typing 76 HLA-B*27 positive and 107 HLA-B*27 negative individuals either by serology or by the ligation based approach. We conclude that ligation based typing is a reliable tool for the DNA based detection of HLA-B*27 alleles. The procedure allows automation to a large extent and should be easily applicable to the typing of other HLA-class I alleles.

Base Sequence↗
PubMed1995

Association of X-linked adrenoleukodystrophy with HLA DRB1 alleles.

Inflammatory demyelination in the central nervous system in the childhood cerebral phenotype of X-linked adrenoleukodystrophy (X-ALD) bears resemblance to that of multiple sclerosis. With a view to an association of HLA class II genes, specifically HLA-DRB1 subtype DRB1*15 to multiple sclerosis we investigated the HLA class II DR haplotype in 29 unrelated X-ALD patients including 17 childhood cerebral phenotype patients. Our results did not show an association of DRB1*15 and X-ALD, but disclosed a significant association of HLA DRB1*16 alleles and X-ALD in general. This finding suggests that in addition to the X-chromosomal ALD gene an autosomal gene linked to the HLA class II region is involved in the pathogenesis of X-ALD. This gene should affect a pathomechanism common to all ALD variants, such as defective peroxisomal metabolism of very long chain fatty acids.

Adrenoleukodystrophy↗
PubMed1995

Conservation of a maternal-specific methylation signal at the human IGF2R locus.

The human IGF2R gene has been reported to be either biallelically or very rarely monoallelically expressed, in contrast to the maternally expressed mouse counterpart. We describe here an analysis of the 5' portion of the human IGF2R gene and show that it contains a maternally methylated CpG island in the second intron. A similar maternally methylated intronic element has been proposed to be the imprinting box for the mouse gene and although the relevance of this element has yet to be directly demonstrated, methylation has been reported to be essential to maintain allele-specific expression of imprinted genes. Allelic expression analysis of human IGF2R in 70 lymphoblastoid cell lines identified only one line showing monoallelic expression. Thus, in this tissue monoparental methylation of the IGF2R gene does not correlate with allele-specific expression. We also confirm here that the human IGF2R gene is located in an asynchronously replicating chromosomal region, as are all other imprinted genes so far analyzed. The mouse and human IGF2R intronic CpG islands both contain numerous large direct repeats that are methylated following maternal, but not paternal, transmittance. Thus features that attract maternal-specific methylation are conserved between the mouse and human genes. Since these intronic CpG islands share organizational rather than sequence homology, this suggests that secondary DNA structure may play a role in attracting a maternal methylation imprint.

Alleles↗
PubMed1995

A combination of two distinct in vitro amplification procedures for DNA typing of HLA-DRB and -DQB 1 alleles.

The differential hybridisation of oligonucleotide probes to polymerase chain reaction (PCR)-amplified DNA has become a standard procedure for tissue typing. We describe a typing method in which differential ligation replaces differential hybridisation, which is a significant simplification of this strategy. After amplification by the PCR two labelled, sequence-specific oligonucleotides hybridise, in the fluid phase, to one strand of heat-denatured amplification product in juxtaposition. In the case of perfectly complementary sequences surrounding the gap, a thermostable ligase catalyses the ligation of the two oligonucleotides, otherwise they stay separated. The use of heat-resistant ligase enables easy repetition of the denaturation-annealing-ligation cycle in a thermocycler. The ligation products are detected by an enzyme linked immunosorbent assay. We tested this typing approach in a model system, the characterisation of three functional alleles of HLA-DRB3 using three probe pairs. No discrepancies were observed in typing 100 individuals of known genotypes. A total of 33 probe pairs combined with generic and group-specific amplification allowed the typing of alleles of HLA-DRB and -DQB1 loci at low resolution. We confirmed ligation-based typing results of 259 individuals with sequence-based HLA-DRB1 typing and HLA-DQB1 typing using PCR with sequence-specific primers (SSPs). In addition, more than 1,500 ligation-based HLA-DRB1 typings were concordant with SSP typing. Excellent signal-to-noise ratios in the enzyme-linked immunosorbent assay make ligation-based typing remarkably robust. The time requirement of 2.5 h post-PCR enables practicable typing of putative organ donors. The whole procedure is more easily amenable to automation than methods based on differential hybridisation requiring additional incubators and extra handling for hybridisation and washing.

Alleles↗
PubMed1994

X-linked adrenoleukodystrophy (ALD): a novel mutation of the ALD gene in 6 members of a family presenting with 5 different phenotypes.

Fragments of the adrenoleukodystrophy (ALD) cDNA from a patient with adolescent ALD were amplified by polymerase chain reaction and subcloned. Bidirectional sequencing of the entire coding ALD gene disclosed a cytosine to guanine transversion at nucleotide 1451 in exon five, resulting in substitution of proline 484 by arginine. Five of nine siblings of the patient, comprising two cerebral ALD, one adrenomyeloneuropathy, one Addison only as well as the symptomatic mother (all accumulating very long chain fatty acids) carried this mutation, which was not found in the unaffected persons, in five unrelated ALD patients, and in twenty controls. We propose that this missense mutation generated the disease per se as well as the metabolic defect; the different phenotypes, however, must have originated by means of additional pathogenetic factors.

Adolescent↗